Body Protection

ABSTRACT

This invention relates to a structure for absorption and/or dissipation of mechanical shocks comprising:
         connectors forming an aerated base with a base surface;   protuberances, each of the protuberances comprising a central axis along which it extends from the aerated base, the central axis being normal to the base surface, two adjacent protuberances being connected to each other by a connector.       

     It also relates to a body protector at least partly made using the structure and protective clothing comprising at least one such protector.

TECHNICAL FIELD OF THE INVENTION

This invention relates to the technical field of body protection andmore particularly the technical field of structures for the absorptionand/or dissipation of mechanical shocks, body protectors and protectiveclothing.

BACKGROUND ART

The term “body protector” usually refers to an arrangement of materialsthat absorb and/or dissipate energy generated during an impact in orderto give some protection to the part of the body facing the protectionunder normal conditions of use. This energy absorbing and/or dissipatingmaterial may or may not be structured.

Such body protectors are usually incorporated into protective clothesworn when engaging in a particular activity, and particularly for partsof the body to be protected against mechanical shocks. Examples of thesezones include the shoulders, elbows, forearms, hips, knees, upper partof the tibia, middle part of the tibia, lower part of the tibia, theentire tibia, the back or the head.

Examples of such body protectors are presented in standards EN1621-1:2013 and EN1621-2: 2014 relating to clothes for protection againstmechanical shocks for motor cyclists.

These body protectors usually have to be made of a material capable ofabsorbing and/or dissipating forces generated during a mechanical shock.However, other criteria must also be considered to provide bodyprotectors that are comfortable to wear. Thus, body protectors should beflexible to adapt to the shape of the part of the body to be protected,particularly the joints, enable the wearer to move freely, be lightweight and breathable.

A more specific example is presented for example in document EP 2399470.The protection element described in this document comprises a base andprotuberances, each of the protuberances extending from the base andnormal to it. The protuberances also include a through orifice.

Each of the protuberances is either a solid of revolution around acentral axis (in other words the external wall and the internal wall ofthe protuberances are right cylinders with a circular base), or a solidwith rotational symmetry of order 6 with a regular hexagonal base. Thebase in this case is not aerated, in other words there are no otherorifices in the material, apart from the orifices passing through theprotuberances. Due to the presence of through orifices, the protectionelement and the body protector have some breathability, but it would beuseful to make the material even more breathable while maintaining shockresistance properties.

Another solution would be to make elastomer nets like those described inWO99/56570, but according to current knowledge, such nets do not havesufficient resistance to shocks under conditions dictated by standards,particularly those mentioned above.

Thus, there is still a need for a protection element for absorptionand/or dissipation of mechanical shocks. Such a protection elementshould preferably be made sufficiently absorbent and/or dissipating,sufficiently breatheable, sufficiently lightweight, sufficientlyflexible, sufficiently resistant at high and low temperatures andsufficiently comfortable.

SUMMARY OF THE INVENTION

The authors have succeeded in obtaining a satisfactory protectionelement, but only after long and unsuccessful trial and error.

Thus, this invention relates to a protection element in the form of astructure for the absorption and/or dissipation of mechanical shocks,comprising:

connectors forming an aerated base with a base surface; and

protuberances, each of the protuberances comprising a central axis alongwhich it extends from the aerated base, the central axis being normal tothe base surface, two adjacent protuberances being connected to eachother by a connector.

This structure is sufficiently aerated and at the same time conferssatisfactory mechanical shock resistance properties.

In this description, the term “aerated base” means a base with orificesother than facing the orifices in the protuberances, if any. Thus, thebase of the structure of the protection element in document EP 2399470is not aerated according to the sense of this invention, while the baseshown in the appended FIGS. 1 to 4 is aerated. In the examplesillustrated on these figures, the aerated nature of the base isconferred particularly by the spaces between connectors. Furthermore,the fact that it is specified that the connectors form the aerated basemakes it clear that the base is composed of connectors only.

The term “base surface” always refers to the surface of the aerated basefrom which the protuberances extend.

The term “normal” and its derivatives should be understood in thegeometric sense. Thus, throughout this presentation, when a normalrelationship is mentioned in relation to the base surface, it should beunderstood that this relationship is contemplated at the consideredlocation and that the term “normal” means “perpendicular” to the tangentplane of the base surface at the considered location. For example, thecentral axis of a protuberance is said to be normal to the base surfacewhen, at the location of the central axis of the protuberance, the axisis perpendicular to the tangent to the base surface at this location.

The base surface can be plane, and in this case the concepts ofnormality and perpendicularity are the same. The base surface can becurved so as match the contours of the part of the wearer's body againstwhich the structure is placed, to protect this part of the body.

Preferably, the breathability of the structure is 10 to 70%, preferably18.5 to 58.5%, preferably 20 to 52.5%, preferably 26.5 to 46.5%, andpreferably about 35%. This ensures sufficient aeration of the structure,making it more comfortable to wear the body protector and to wear theprotective clothing inside which the protector is provided, even duringintense physical activity.

Breathability is defined at the base surface and corresponds to the areaof the base surface corresponding to an empty space as a percentage ofthe total area of the base surface.

Furthermore or alternately, the Shore A hardness of the structure is 5to 90, preferably 11.5 to 68.5, preferably 18.5 to 46.5, and preferablyabout 25. Thus, the structure particularly meets the necessaryrequirements to achieve performance level 2 in standard EN1621-1: 2013and/or performance level 1 in standard EN1621-2: 2014.

The Shore A hardness is measured with a durometer in accordance withstandard DIN 53505: 2009.

Furthermore or alternatively, the ratio between the height of theprotuberances and the thickness of the aerated base is 6 to 17,preferably 6.5 to 8.5, preferably 6 to 8, and preferably about 7.5. Thisratio ensures light weight, breathability and mechanical strengthproperties of the structure.

The height of protuberances is the height measured from the base surfaceof the aerated base from which the protuberances extends up to the freeends of the protuberances, parallel to the central axis of theprotuberances. If the free end of the protuberances is not parallel tothe base surface, the level at the longest distance will be considered.

The thickness of the aerated base is the thickness of the connectors(see below).

The connectors are preferably cylindrical in shape, the directrix of thecylinder being colinear with the base surface. Thus, they can be in theform of a strip with plane surfaces (cylindrical with rectangular base).Alternatively, the connectors have a non-cylindrical shape, such as adomed or scooped strip. Preferably, the surface of the strips has aplane central part and two external parts tilted relative to the centralpart such that the cross-section of the connector colinear with thedirectrix and perpendicular to the base surface decreases withincreasing distance from the central part. The cylinder may also have acircular or polygonal base (preferably a regular polygon such as asquare or hexagon).

The connectors advantageously form a mesh pattern in which at least someand possibly all of the nodes are occupied by a protuberance.Preferably, the mesh pattern is homogeneous, in other words it is a meshformed from a repeating pattern. Still preferably, the mesh pattern maybe regular, in other words the pattern unit is a regular polygon. Thepattern unit may be composed of 2, 3, 4, 5, 6, 7 or 8 connectors.

Furthermore or alternatively, the length of the connectors is 0.01 to 25mm, preferably 0.50 to 17.5 mm, preferably 1.0 mm to 9.5 mm, andpreferably 1.7 mm. The length of a connector is measured parallel to thebase surface and between the external walls of the protuberances thatthe connector connects directly and physically. The external wall of theprotuberances may be curved, in this case the shortest length will beused.

Furthermore or alternately, the thickness of the connectors is 0.1 to1.4 mm, preferably 0.35 to 1.2 mm, preferably 0.55 to 1 mm, andpreferably about 0.80 mm.

The thickness of the connectors, that is also the thickness of theaerated base, is measured normal to the base surface. The thickness ofthe connectors is not necessarily constant over the entire surface ofthe connectors, and in this case “thickness” should be understood tomean the maximum thickness. Thus, if each connector is a strip domed atits centre, the thickness is taken at the centre; on the other hand, ifeach of the connectors is a scooped strip, the thickness is taken at itslateral edges.

Furthermore or alternatively, the width of the connectors is 0.3 to 25mm, preferably 1.2 to 17.5 mm, preferably 2.0 to 10.5 mm, and preferablyabout 3.0 mm.

Furthermore or alternatively, the ratio between the equivalent outsidediameter of the protuberances measured at the base surface and thedistance between the central axes of two adjacent protuberances is 0.65to 1.5, preferably 0.76 to 0.93, preferably 0.8 to 0.89, and preferablyabout 0.85. Such a ratio ensures an optimum flexibility of the structurewithout loss of mechanical properties providing protection.

The equivalent outside diameter is the diameter of a circle inside whichthe external wall of the protuberance, taken perpendicular to thecentral axis, is inscribed with a maximum of common points between thecircle and the external wall of the protuberance.

Furthermore or alternatively, the distance between two adjacentprotuberances is 6 to 60 mm, preferably 7.5 to 43.5 mm, preferably 9.5to 27.5 mm, and preferably about 11 mm. The distance between twoadjacent protuberances is taken between the central axes of theseprotuberances and parallel to the base surface.

In one particular embodiment, all the protuberances are on the same sideof the aerated base. Alternatively, the protuberances are present oneach side of the aerated base, preferably the central axes of theprotuberances on one side of the aerated base are aligned with thecentre axes of the protuberances on the other side of the aerated base.As a variant, the central axes of the protuberances on one side of theaerated base are in staggered rows with the central axes of theprotuberances on the other side of the aerated base. In the case inwhich the protuberances are present on both sides of the aerated base,the aerated base will have two base surfaces. In the case in which thecharacteristics depend on a base surface, the base surface to beconsidered will be the base surface from which the consideredprotuberance extends.

In one embodiment, each protuberance has an external wall that has acircular symmetry about the central axis. As a variant, eachprotuberance has an external wall that can be superposed on its imageobtained by a 360°/n rotation about the central axis, where n is greaterthan 1, preferably greater than 2, preferably 2 to 10, preferably 3 to10, preferably 4 to 8, preferably 5 to 7, and preferably 6. For example,the transverse cross section of the external wall is a regular polygonwith 3 to 10 vertices, preferably 4 to 8, preferably 5 to 7, andpreferably 6.

In one embodiment, the equivalent outside diameter of the protuberancesis constant from the aerated base. This means that the protuberances areright cylinders (in the mathematical sense). As a variant, theequivalent outside diameter of the protuberances decreases linearly fromthe aerated base with an angle of more than 0° and equal or less than30°, preferably more than 2° and equal or less than 15°, preferably morethan 4° and equal or less than 8°, and preferably equal to about 6°. Theangle of 6° is particularly suitable for easy stripping of the structurefrom its mould.

Furthermore or alternatively, the equivalent outside diameter at thebase surface is 3 to 25 mm, preferably 5 to 20 mm, preferably 7 to 14mm, and preferably about 9.5 mm.

Furthermore or alternatively, each of the protuberances has a throughorifice therein which extends along the central axis, and defines aninternal wall of the protuberance. This makes it possible to increasebreathability of the structure and reduce its weight at the same time.As a variant, the orifice is not a through orifice but a orifice whichis blind on the side of the aerated base, which reduces the weight ofthe structure without modifying its breathability.

In one embodiment, the internal wall has a circular symmetry about thecentral axis. As a variant, the internal wall can be superposed on itsimage by 360°/n rotation about the central axis, where n is greater than1, preferably greater than 2, preferably 2 to 10, preferably 3 to 10,preferably 4 to 8, preferably 5 to 7, and preferably 6. For example, thetransverse cross section of the internal wall is a regular polygon with3 to 10 vertices, preferably 4 to 8, preferably 5 to 7, and preferably6. In the latter case, if the transverse cross section of the externalwall is also a regular polygon, it preferably has the same shape as thetransverse cross section of the internal wall and the vertices of thesepolygons are angularly aligned.

In one embodiment, the equivalent inside diameter of the protuberancesis constant from the aerated base. The equivalent inside diameter is thediameter of a circle inside which the internal wall of the protuberance,taken perpendicular to the central axis, is inscribed with a maximum ofcommon points between the circle and the internal wall of theprotuberance. Alternatively, the equivalent inside diameter of theprotuberances decreases linearly from the base surface with an angle ofmore than 0° and equal or less than 30°, preferably more than 2° andequal or less than 15°, preferably more than 4° and equal or less than8°, and preferably equal to about 6°. Alternatively, the equivalentinside diameter of the protuberances increases linearly from the basesurface with an angle of more than 0° and equal or less than 30°,preferably more than 2° and equal or less than 15°, preferably more than4° and equal or less than 8°, and preferably equal to about 6°. An angleof 6° is particularly suitable for easy stripping of the structure fromits mould.

Furthermore or alternatively, the thickness of the protuberance isdefined by the difference between the equivalent inside diameter and theequivalent outside diameter of the protuberance at the base surface. Thethickness of the protuberance is 0.5 to 10 mm, preferably 0.65 to 7 mm,preferably 0.85 to 4 mm, and preferably about 1 mm.

Furthermore or alternatively, the height of the protuberances is 2 to8.5 mm, preferably 3.5 to 7.5 mm, preferably 4.5 to 6.5 mm, andpreferably about 6 mm.

The protuberances are preferably distributed in a regular mesh pattern,for example with a square mesh pattern (each protuberance having fourneighbours) or a regular triangular mesh pattern (each protuberancehaving six neighbours). Consequently, all the connectors have the samelength.

The structure is preferably made of a flexible material. Flexible meansa material for which the global shape can be modified to make it betterfit the shape of the body against which it is placed.

The flexible material is preferably a viscoelastic material, preferablywith a vitreous transition temperature Tg between −20 and 50° C.,preferably between 0 and 40° C., and preferably between 15 and 25° C.The vitreous transition temperature Tg can be obtained by a dynamicmechanical analysis using the ACOEM METRAVIB DMA+450 instrument.Although for manufacturing reasons it is easier to make the aerated baseand the protuberances of the same viscoelastic material, it is alsopossible that the aerated base and the protuberances are made ofdifferent viscoelastic materials. It is also possible in both cases toprovide two or more populations of different protuberances, each beingmade of a different viscoelastic material than the others.

In the remainder of this presentation, the quantities of compounds usedin the composition of the viscoelastic material are expressed by weightrelative to the total weight of the viscoelastic material.

The majority constituent of the viscoelastic material is a polymer suchas polynorbornene, polyacrylonitrile, polyvinyl chloride (PVC), ethylenevinyl acetate (EVA) copolymer, chlorobutyl rubber and mixtures thereof,preferably polynorbornene alone or a mixture of polynorbornene with atleast one of the other polymers mentioned above. By majority constituentis the constituent present in the largest quantity in the viscoelasticmaterial should be understood.

The viscoelastic material can advantageously include 27 to 55% ofpolynorbornene, preferably 40 to 50%, preferably 42 to 48%, andpreferably about 45%.

The viscoelastic material can also include a plasticiser such as an oil.Aromatic oils are preferred but a paraffin oil (PA), a naphthene oil(HNA), a silicone oil or C9 resins (particularly those supplied byKonimpex under the name “Hydrocarbon C9”) can also be used. Theviscoelastic material advantageously includes 33 to 50% of plasticiser,preferably 37 to 45%, preferably 39 to 43% by weight, and preferablyabout 40%.

The viscoelastic material can also include a filler such as silicapowder, kaolin powder, aluminium oxide (Al(OH)₃) powder, stearic acidpowder or a mixture thereof. The viscoelastic material advantageouslyincludes 4 to 8% of filler, preferably 5 to 7%, preferably 5.5 to 6.5%,and preferably about 6%.

The viscoelastic material can also include other compounds such as apreservative, an anti-oxidant, a UV stabiliser, an anti-scratch agent, avulcanising agent, a vulcanisation accelerator and a colouring agent.

Examples of preservatives are aluminium hydroxide (Al(OH)₃), metaloxides such as zinc oxide (ZnO) or titanium dioxide (TiO₂), ethylenevinyl acetate (EVA), and an ethylene propylene diene monomer (EPDM). Theviscoelastic material may also not contain any preservatives.

Examples of anti-oxidants are phenolic anti-oxidants (for example 2,6di-ter-butyl-4-methyl phenol), phenyl-p-phenylenediamine and derivativesthereof such as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine(6PPD); the preferred antioxidants being phenyl-p-phenylenediamine and6PPD.

Examples of UV stabilisers are paraffin waxes and metal oxides such aszinc oxide (ZnO) or titanium dioxide (TiO₂).

One example of an anti-scratch agent is N-(cyclohexylthio)-phthalmide.

Examples of vulcanising agents include sulphur and di(benzothiazol-2-yl)disulphide (MBTS).

Examples of vulcanisation accelerators include titanium dioxide (TiO₂),N-cyclohexyl-2-benzothiazole sulphenamide (CBS),bis(N,N-dimethylthiocarbamyl) disulphide, stearic acid, mixtures ofaccelerators such as Deovulc EG 3 which is a synergistic combination ofhighly active accelerators containing ethylenethiourea, available fromDOG Deutsche Oelfabrik and King Industries, Inc., and metal oxides suchas zinc oxide (ZnO) or titanium oxide (TiO₂), preferably stearic acid ormixtures of accelerators such as Deovulc EG 3.

Examples of colouring agents are preferably organic and inorganicpigments such as iron oxides (such as yellow or red oxides), titaniumdioxide (TiO₂), zinc oxide (ZnO) or carbon black.

The structure for absorption and/or dissipation of mechanical shocks canbe completely homogeneous, in other words its connectors andprotuberances are arranged at regular intervals over the entirestructure forming a single pattern and the structure for absorptionand/or dissipation of mechanical shocks is made of a single material.Alternatively, the absorption and/or dissipation structure can compriseseveral different zones. These zones can be different from each othereither by at least one dimension of one of its elements (connectors,protuberances), or by the material used to form the zones, or by atleast one dimension of one of its elements and also by the material usedto form the zones.

The invention also relates to a body protector made at least partiallyusing the structure for absorption and/or dissipation of mechanicalshocks described above.

For the purposes of this presentation, the term “body protector” means astructure for absorption and/or dissipation of mechanical shocks withappropriate dimensions or an arrangement of such structures withappropriate dimensions to provide a certain degree of protection to thepart of the body facing the protection under normal conditions of use.

In its simplest embodiment, the body protector is made entirely from thestructure for absorption and/or dissipation of mechanical shocks asdescribed above.

Examples of body protector shapes are as given in standards EN1621-1:2013 and EN1621-2: 2014 relating to clothes for protection againstmechanical shocks for motor cyclists.

The body protector can be generally plane, in other words the aeratedbase of the structure for absorption and/or dissipation of thermalshocks of which it is made is itself plane. Thus, when it is integratedinto protective clothing, the body protector is folded, the free ends ofthe protuberances moving towards or away from each other. Theflexibility of the body protector can be increased by making generallyV-shaped cuts in it, the tip of the V facing the inside of the protectorand the diagonals extending to the edge of the protector. The diagonalsof the V may be straight or curved. If the diagonals of the V arecurved, they are curved on the same side. When folding, the diagonals ofthe V move towards each other and are then generally sealed to eachother, for example by gluing or welding, the protector then forming adish usually to contain the head or a joint such as the shoulder, elbowor knee. A small circular cutout can be provided at the tip of the V tomake it easier to fold the body protector at this location. Small inthis case means a circular cutout with a diameter of less than 5 mm.

The body protector can also be curved, in other words it does not needto be folded before it is incorporated into protective clothing: italready has the right curvature adapted to the part of the body to beprotected. Thus, the structure for absorption and/or dissipation ofmechanical shocks is directly shaped in the final use shape of the bodyprotector.

In particular, the body protector at least satisfies performance level 1given in standard EN1621-1: 2013 or in standard EN1621-2: 2014,preferably performance level 2. In particular, the body protector atleast satisfies performance level 2 given in standard EN1621-1: 2013 andperformance level 1 in standard EN1621-2: 2014.

The invention relates particularly to protective clothing comprising abody protector as described above.

DESCRIPTION OF THE DRAWINGS

The appended drawings are given for illustrative and non-limitativepurposes to help the reader better understand this invention. Thesedrawings include the following figures:

FIG. 1 is an oblique projection view of a particular embodiment of thestructure for absorption and/or dissipation of mechanical shocksaccording to the invention with cylindrical protuberances with acircular base;

FIG. 2 is an oblique projection view of a particular embodiment of thestructure for absorption and/or dissipation of mechanical shocksaccording to the invention with cylindrical protuberances with a regularhexagon shaped base;

FIG. 3 is a cross section perpendicular to the aerated base passingthrough the central axis of the protuberances; and

FIG. 4 is a top view of a protector according to the invention madeentirely using the structure for absorption and/or dissipation ofmechanical shocks according to the invention.

DESCRIPTION OF THE INVENTION

The same numeric references are used to designate equivalent elements inall the figures.

One particular example of the absorption and/or dissipation structureaccording to the invention is described below with reference to FIG. 1.The structure 1 is homogeneous.

This structure 1 for absorption and/or dissipation of mechanical shockscomprises connectors 2 forming a plane aerated base B with a basesurface. The connectors are in the form of a strip with plane surfaceswith the same length.

The structure 1 for absorption and/or dissipation of mechanical shocksalso includes protuberances 3, each of the protuberances comprising acentral axis AA along which it extends from the aerated base B, thecentral axis AA being normal to the base surface.

The protuberances 3 are present on only one side of the aerated base B.Each protuberance 3 has an external wall 31, the external wall 31 havinga circular symmetry about the central axis. Each of the protuberances 3has a through orifice which extends along the central axis AA anddefining an internal wall 33 of the protuberance 3. The internal wall 33has a circular symmetry about the central axis AA. The protuberances 3are distributed in a regular triangular mesh pattern, in other wordseach of the protuberances has six neighbours and the central axes of theneighbours form a regular hexagon.

Another particular example of the absorption and/or dissipationstructure according to the invention is described below with referenceto FIG. 2. The structure 1 is homogeneous.

This structure 1 for absorption and/or dissipation of mechanical shockscomprises connectors 2 forming a plane aerated base B with a basesurface. The connectors are in the form of a strip with plane surfaceswith the same length.

The structure 1 for absorption and/or dissipation of mechanical shocksalso includes protuberances 3, each of the protuberances comprising acentral axis AA along which it extends from the aerated base B, thecentral axis AA being normal to the base surface.

The protuberances 3 are present on only one side of the aerated base B.Each protuberance 3 has an external wall 31, the transverse crosssection of the external wall 31 being a regular polygon with 6 vertices(regular hexagonal polygon). Each of the protuberances 3 has a throughorifice which extends along the central axis AA and defines an internalwall 33 of the protuberance 3. The transverse cross section of theinternal wall 33 is a regular polygon with 6 vertices. The vertices ofthe regular polygons forming the transverse cross section of theexternal and internal walls are angularly aligned. The protuberances 3are distributed in a regular triangular mesh pattern, in other wordseach of the protuberances has six neighbours and the central axes of theneighbours form a regular hexagon.

FIG. 3 shows an exemplary cross section perpendicular to the aeratedbase for the exemplary structures for absorption and/or dissipation ofmechanical shocks of FIGS. 1 and 2.

On FIG. 3, the equivalent outside diameter D_(e) of the protuberances 3decreases linearly from the aerated base B with an angle of 6° while theequivalent inside diameter D_(i) of the protuberances 3 increaseslinearly from the aerated base B at an angle of 6°.

An example of the dimensions of the different elements of the structurefor absorption and/or dissipation of mechanical shocks is given in table1 below.

TABLE 1 Structure for absorption and/or dissipation of mechanical shocksthickness 6.8 mm Protuberances height   6 mm equivalent outside diameterat the 9.5 mm aerated base protuberance thickness   1 mm Connectorslength 1.7 mm width   3 mm thickness 0.8 mm

Table 2 below gives an exemplary composition for the material used forthe structure for absorption and/or dissipation of mechanical shocks.Quantities are expressed as a percentage by weight of the totalcomposition.

TABLE 2 Polynorbornene 45% Oils 40% Silica 6% Anti-scratch agent 1%Vulcanising agent (sulphur) 1% Vulcanisation accelerator 1% Colouringagent 1% Stearic acid <1% Antioxidant <1% UV stabiliser (wax) <1% Thetotal does not add up to 100%, due to approximations.

The structure for absorption and/or dissipation of mechanical shockswith one of the configurations of FIGS. 1 to 5 and with the compositiongiven in table 2 has a breathability of about 35% and a Shore A hardnessof about 25. This structure make it possible to reach performance level2 for standard EN1621-1 and level 1 for standard EN1621-2.

An exemplary body protector is described below with reference to FIG. 4.This exemplary body protector corresponds to the examples given instandard EN1621-1: 2013 (see FIG. 1 and table 1 in this standard). Thebody protector 10 can easily be defined using three parameters: tworadii r₁, r₂ and a length l. It comprises three parts centred on alongitudinal axis BB which is also an axis of symmetry of the bodyprotector 10. A first end part 11 has the shape of a half-circle withradius r₁ and a second end part 12 has the shape of a half-circle withradius r₂. The two end parts 11, 12 are connected to each other by atrapezoidal shaped central part 13 with the longitudinal axis BB as theaxis of symmetry and height l.

Such a shape can be used to protect the following parts of the body:shoulder (S); elbow and forearm (E); hip (H); knee and upper part of thetibia (K); knee, upper and middle parts of the tibia (K+L); lower partof the tibia (L).

Table 3 below gives the minimum dimensions of the three parametersaccording to standard EN1621-1: 2013.

TABLE 3 Small model Large model Type r₁ r₂ l r₁ r₂ l S 55 32 64 70 40 80E 45 24 118 50 30 150 K 55 24 100 70 30 130 H 35 26 70 44 33 88 L 32 2464 40 30 80 K + L 55 24 185 70 30 240

1. Structure for absorption and/or dissipation of mechanical shockscomprising: connectors forming an aerated base with a base surface;protuberances, each of the protuberances comprising a central axis alongwhich it extends from the aerated base, the central axis being normal tothe base surface, two adjacent protuberances being connected to eachother by a connector.
 2. Structure according to claim 1, wherein theratio between the height of the protuberances and the thickness of theaerated base is 6 to
 17. 3. Structure according to claim 1, whereinbreathability of the structure is 10 to 70%.
 4. Structure according toclaim 1, wherein the Shore A hardness of the structure is 5 to
 90. 5.Structure according to claim 1, wherein the ratio between the equivalentoutside diameter of the protuberances measured at the base surface andthe distance between the central axes of two adjacent protuberances is0.65 to 1.5.
 6. Structure according to claim 1, wherein theprotuberances are all on the same side of the aerated base.
 7. Structureaccording to claim 1, wherein each protuberance has an external wallwhich has a circular symmetry about the central axis or can besuperposed on its image by a 360°/n rotation about the central axis,where n is an integer greater than
 1. 8. Structure according to claim 1,wherein the equivalent outside diameter of the protuberances is constantfrom the aerated base or decreases linearly from the aerated base withan angle of more than 0° and equal or less than 30°.
 9. Structureaccording to claim 1, wherein each of the protuberances has a through orblind orifice therein, and which extends along the central axis anddefines an internal wall of the protuberance.
 10. Structure according toclaim 1, wherein the internal wall has a circular symmetry about thecentral axis or can be superposed on its image by a 360°/n rotationabout the central axis, where n is an integer greater than
 1. 11.Structure according to claim 1, wherein the equivalent inside diameterof the protuberances: is constant from the aerated base or decreaseslinearly from the aerated base with an angle of more than 0° and equalor less than 30°, or increases linearly from the aerated base with anangle of more than 0° and equal or less than 30°.
 12. Structureaccording to claim 1, wherein the structure is made of a viscoelasticmaterial.
 13. Structure according to claim 12, wherein the majorityconstituent of the viscoelastic material is a polymer.
 14. Bodyprotector made at least partially from the structure according toclaim
 1. 15. Body protector according to claim 14 achieving at leastperformance level 1 in standard EN1621-1: 2013 or in standard EN1621-2:2014.
 16. Protective clothing comprising at least one protectoraccording to claim
 14. 17. Structure according to claim 1, wherein theprotuberances are on each side of the aerated base.
 18. Structureaccording to claim 1, wherein each protuberance has an external wallwhich can be superposed on its image by a 60°/n rotation about thecentral axis.
 19. Structure according to claim 1, wherein eachprotuberance has an internal wall which can be superposed on its imageby a 60°/n rotation about the central axis.
 20. Structure according toclaim 12 wherein the majority constituent of the viscoelastic materialis chosen from the group consisting of: polynorbornene,polyacrylonitrile, polyvinyl chloride (PVC), the ethylene vinyl acetate(EVA) copolymer, chlorobutyl rubber and mixtures thereof.